The present invention relates to a method and apparatus for digitally printing on textile or fabric articles.
As is known, a great drawback of the printing methods for digitally printing on fabric materials, is an impossibility of achieving an even penetration, i.e. a two-face vision, as colored areas which are colored with a different chromatic saturation must be imprinted.
In particular, it is practically impossible to obtain a satisfactory two-face vision on fabric materials, if light color areas must be made thereon.
Such a limitation is strictly bound to the digital printing concept, since, in order to provide a clear or light color shading (a low amount of color) it is necessary to deposit a set amount of ink (corresponding to the desired tone pattern) which, for clear or light tone patterns is much less than that necessary for dark tone patterns (a full tone pattern).
To a limited amount of ink, actually, also corresponds a limited impregnation of the receiving fabric material, and, accordingly, a poor penetration, in a case in which one desires to provide a bi-face printing effect, such as flags, curtains, foulards and so on.
Such a limitation has not been up to now solved and technically overcome.
The above mentioned drawback, in particular, limits and negatively affects the use of the digital printing technology, mainly in those areas where, on the contrary, it could express great advantages from an application flexibility standpoint.
Such a limitation, actually, cannot be detected in conventional printing methods, such as screen printing, and roto-printing methods, since the amount of ink deposited for surface unit is herein constant and, anyhow, can be controlled by parameters different from those expressed in the digital printing technology.
FIG. 1 schematically shows an example of a printing method for printing on a fabric material, by a conventional procedure, in particular a screen printing procedure.
As shown in this figure, the printing paste amount is specifically identical both in a clear or light color embodiment and in a dark fabric embodiment.
This characteristic allows to deposit a like color volume and, accordingly, to achieve a desired depth through the fabric material, thereby providing an acceptable bi-face vision, which feature is indispensable for printing upon articles such as flags, curtains and foulards and so on.
FIG. 2 shows a printing example in which a conventional digital printing method is used.
As clearly shown in FIG. 2, in such a digital application, the concentration of dye in the ink is a fixed one, and only the volume amount thereof can be changed.
Accordingly, for providing clear or light color areas, it is necessary to apply small amounts of inks, whereas, for dark colors, it would be possible to use comparatively high ink amounts.
This would constructionally hinder the penetration capability of clear colors with respect to dark colors, and an acceptable two-face vision would not be achieved.
In fact, only the dark colors or dyes are able to penetrate to a desired or target depth, whereas the clear dyes would be necessarily arranged only on the top surface of the support or fabric material.
Several searches have been carried out for solving the above mentioned problem, by using a lot of different approaches, for example by impregnating the fabric material before printing thereon, by using substances designed for improving the penetration of the ink material through the fabric.
However, since this would be an application generalized on the overall fabric, it is not possible to operate in a selective manner, and accordingly, as efficiently as desired.